This invention relates generally to rectilinear motion proportional solenoids and has application to solenoids which produce a motion-directed output which is linearly proportional to the electrical input current applied to the coil of the solenoid.
Linear proportional solenoids are shown and described in U.S. Pat. Nos. 4,463,332; 4,767,097; and 4,835,503. In each of these patents, the permanent magnet whose magnetic field aids the magnetic field created by the electrical current-induced coil has various operative locations. In U.S. Pat. Nos. 4,463,332 and 4,767,097 the permanent magnet surrounds the coil. In U.S. Pat. No. 4,835,503 the permanent magnet is placed interiorly of the coil and located in the end face of the polepiece. In each of the aforementioned patents, there are two linear springs which are positioned within the flux path of the solenoid and which carry the moveable armature of the solenoid.
It will be observed that in each of the aforementioned solenoid designs, there are a multiplicity of parts which adds to the overall production costs and general size of the solenoid.